1. Field of the Invention
The invention is to a new laser beam reflector dispersion means in combination with a gauze for use as a shield during laser surgery, or other laser use, to protect persons and/or equipment in the vicinity by dissipating the beam energy in multiple directions.
2. Description of the Related Art
Laser usage has greatly proliferated over the past decade because of the many advantages the laser offers over the scalpel. The laser beam can be pin-pointed in its placement with great accuracy; it cuts without pressure; and it seals off blood vessels upon cutting, thereby greatly reducing the quantity of blood loss during surgery. The laser also represents a greater complexity and danger that must be dealt with effectively in the clinical setting. Safety has become a major concern when working with lasers and more powerful lasers continue to be developed. Numerous accounts of accidents with medical lasers during surgical procedures have been reported by the FDA and others. Injuries to the eye causing blindness is the most frequent devastating accident. Damage to the skin and other body organs has also frequently occurred. Laser beams that are reflected as highly collimated beams off smooth metallic surfaces, typical of surgical instruments and other objects found in the operating room, have been a particular problem that has resulted in serious injuries.
The most common method of protecting the patient from exposure to laser radiation in the operating room is by employing a surgical drape of towels or gauze pads that have been saturated with water or other suitable aqueous solutions, such as saline solutions. The wetted towels or gauze pads are applied adjacent the wound site, or locus of impact, where the surgeon intends to direct the laser beam, with the towel or gauze surrounding the wound site. Only the area to be operated on is left exposed. Additionally, in surgical procedures in the region of the head or neck, or whenever the patient undergoes general anesthesia, the patient's eyes are normally protected by draping the eyes with wetted towels or gauze pads. The time period over which wet towels or gauze pads provide protection depends on the type of laser and the power density of the laser beam. In many cases, the duration of effective protection against laser exposure is less than one second. When using typical power density carbon dioxide lasers, water in the towels is evaporated rapidly. Once the water is evaporated, the drape is no longer effective to protect the underlying tissue. During lengthy operating room procedures, water continually evaporates from the wetted gauze or towel dressings under ambient conditions, reducing the level of protection that was initially provided. When using the shorter wavelength lasers, the radiation is not effectively blocked or absorbed by the wet towel or gauze; it is transmitted to the underlying tissue. Exposure of tissue to the laser can result in serious injury to the patient.
Protective articles have been described in the prior art which seek to improve levels of safety in the operating room during laser surgical procedures. U.S. Pat. No. 4,616,641, issued 14 Oct. 1986 to E. Teeple, describes a surgical shield for use during laser surgical procedures comprised of a fabric sheet positioned between a pair of coextensive metal foil sheets. The preferred inner sheet is cotton gauze and the outer sheets are aluminum foil, with at least one of the foil sheets having an outer matte surface finish. The nature of the matte finish and method of its formation are not described. U.S. Pat. No. 4,635,625, issued 13 Jan. 1987 to E. Teeple, describes a surgical eye mask for use during laser treatment having an outer layer made from a metallic foil to which are secured a pair of gauze eye pads. The metallic foil is disclosed as being "highly reflective" and is intended to be the outer layer of the mask which is first to contact the laser beam. U.S. Pat. No. 4,901,738, issued 20 Feb. 1990 to R. Brink et al, describes a laser shield with an opaque, flexible, fabric sheet having one major surface with a reflective metal foil. The opaque, flexible, fabric sheet represents the outer layer, incident to the laser beam, and the foil represents an immediately underlying layer. The foil has a thickness sufficient to resist puncture by a carbon dioxide laser using 20 watts of power for at least one second. One function ascribed to the flexible fabric sheet is to reduce reflection of the beam. However, since the fabric sheet is rapidly penetrated by the laser beam, exposing the "shiny" metallic surface, protection from the reflected laser beam is very brief and may not be adequate to avert injury from exposure to the reflected beam.
In applicant's co-pending application, a laser barrier of a "gas blown" silicone foam sheet which optionally may contain an underlying layer of metallic foil is disclosed. That laser barrier has demonstrated being effective in stopping penetration of laser beams and of not externally reflecting the laser beam. It provides protection to the patient or underlying object as well as protecting persons or objects from reflected beams. Although that laser barrier is highly useful for many surgical procedures, the cost of the barrier limits its applications, especially for relatively low cost minor surgical and dental procedures where a laser is utilized. Also, the chemical and physical changes which occur to the laser barrier upon impact with the laser beam, cause a reduction in flexibility. Because of this, the barrier is not ideally suited for certain surgical procedures such as a minimally invasive laser surgical procedures which are accomplished within the body cavity without the need for large incisions. In such minimally invasive procedures, the barrier must remain flexible so that it can be passed through the small opening of the body wall after the surgery is completed.
Prior art laser barrier articles do not offer adequate combined protection of both the patient and the operating room staff. The "highly reflective" metallic foil protects the patient but endangers those in the operating room by virtue of specular reflection. Reducing the reflective nature of a thin metal layer by changing the molecular nature of the surface of the metal, such as by anodization, result in absorption of the beam on the surface, followed by meltdown and penetration of the thin metal layer. Application of nonreflective coatings to a thin metal layer surface, also results in absorption of the beam on the surface followed by meltdown and penetration. Applying a fabric layer on the outer surface of a thin metal layer provides only very brief protection before the fabric is vaporized and the exposed shiny metal layer reflects the beam.